import pandas as pd
import numpy as np

if __name__ == '__main__':
    s = pd.Series([1, 2, 3, 'hello', 'spark', np.nan])
    print(s)


    dates = pd.date_range('20190622', periods=7)
    df = pd.DataFrame(np.random.randn(7, 4), index=dates, columns=['A', 'B', 'C', 'D'])
    print(df)